diff --git a/ipc/mscom/AgileReference.cpp b/ipc/mscom/AgileReference.cpp
index 816d15df0c3c..c0fb458e5836 100644
--- a/ipc/mscom/AgileReference.cpp
+++ b/ipc/mscom/AgileReference.cpp
@@ -6,11 +6,10 @@
 
 #include "mozilla/mscom/AgileReference.h"
 
-#include "mozilla/Assertions.h"
 #include "mozilla/DebugOnly.h"
 #include "mozilla/DynamicallyLinkedFunctionPtr.h"
+#include "mozilla/Assertions.h"
 #include "mozilla/Move.h"
-#include "mozilla/mscom/Utils.h"
 
 #if NTDDI_VERSION < NTDDI_WINBLUE
 
@@ -31,34 +30,10 @@ HRESULT WINAPI RoGetAgileReference(AgileReferenceOptions options,
 namespace mozilla {
 namespace mscom {
 
-AgileReference::AgileReference()
-  : mIid()
-  , mGitCookie(0)
-{
-}
-
 AgileReference::AgileReference(REFIID aIid, IUnknown* aObject)
   : mIid(aIid)
   , mGitCookie(0)
 {
-  AssignInternal(aObject);
-}
-
-void
-AgileReference::Assign(REFIID aIid, IUnknown* aObject)
-{
-  Clear();
-  mIid = aIid;
-  AssignInternal(aObject);
-}
-
-void
-AgileReference::AssignInternal(IUnknown* aObject)
-{
-  // We expect mIid to already be set
-  DebugOnly<IID> zeroIid = {};
-  MOZ_ASSERT(mIid != zeroIid);
-
   /*
    * There are two possible techniques for creating agile references. Starting
    * with Windows 8.1, we may use the RoGetAgileReference API, which is faster.
@@ -71,7 +46,7 @@ AgileReference::AssignInternal(IUnknown* aObject)
   MOZ_ASSERT(aObject);
 
   if (pRoGetAgileReference &&
-      SUCCEEDED(pRoGetAgileReference(AGILEREFERENCE_DEFAULT, mIid, aObject,
+      SUCCEEDED(pRoGetAgileReference(AGILEREFERENCE_DEFAULT, aIid, aObject,
                                      getter_AddRefs(mAgileRef)))) {
     return;
   }
@@ -82,7 +57,7 @@ AgileReference::AssignInternal(IUnknown* aObject)
     return;
   }
 
-  DebugOnly<HRESULT> hr = git->RegisterInterfaceInGlobal(aObject, mIid,
+  DebugOnly<HRESULT> hr = git->RegisterInterfaceInGlobal(aObject, aIid,
                                                          &mGitCookie);
   MOZ_ASSERT(SUCCEEDED(hr));
 }
@@ -97,16 +72,7 @@ AgileReference::AgileReference(AgileReference&& aOther)
 
 AgileReference::~AgileReference()
 {
-  Clear();
-}
-
-void
-AgileReference::Clear()
-{
-  mIid = {};
-
   if (!mGitCookie) {
-    mAgileRef = nullptr;
     return;
   }
 
@@ -118,27 +84,13 @@ AgileReference::Clear()
 
   DebugOnly<HRESULT> hr = git->RevokeInterfaceFromGlobal(mGitCookie);
   MOZ_ASSERT(SUCCEEDED(hr));
-  mGitCookie = 0;
-}
-
-AgileReference&
-AgileReference::operator=(AgileReference&& aOther)
-{
-  Clear();
-  mIid = aOther.mIid;
-  aOther.mIid = {};
-  mAgileRef = std::move(aOther.mAgileRef);
-  mGitCookie = aOther.mGitCookie;
-  aOther.mGitCookie = 0;
-  return *this;
 }
 
 HRESULT
-AgileReference::Resolve(REFIID aIid, void** aOutInterface) const
+AgileReference::Resolve(REFIID aIid, void** aOutInterface)
 {
   MOZ_ASSERT(aOutInterface);
   MOZ_ASSERT(mAgileRef || mGitCookie);
-  MOZ_ASSERT(IsCOMInitializedOnCurrentThread());
 
   if (!aOutInterface) {
     return E_INVALIDARG;
@@ -178,7 +130,7 @@ AgileReference::Resolve(REFIID aIid, void** aOutInterface) const
   return originalInterface->QueryInterface(aIid, aOutInterface);
 }
 
-/* static */ IGlobalInterfaceTable*
+IGlobalInterfaceTable*
 AgileReference::ObtainGit()
 {
   // Internally to COM, the Global Interface Table is a singleton, therefore we
diff --git a/ipc/mscom/AgileReference.h b/ipc/mscom/AgileReference.h
index fb2d6e16926f..e1ef9b3ed350 100644
--- a/ipc/mscom/AgileReference.h
+++ b/ipc/mscom/AgileReference.h
@@ -33,17 +33,9 @@ namespace mscom {
  * HRESULT hr = myAgileRef->Resolve(IID_IFoo, getter_AddRefs(foo));
  * // Now foo may be called from the main thread
  */
-class AgileReference final
+class AgileReference
 {
 public:
-  AgileReference();
-
-  template <typename InterfaceT>
-  explicit AgileReference(RefPtr<InterfaceT>& aObject)
-    : AgileReference(__uuidof(InterfaceT), aObject)
-  {
-  }
-
   AgileReference(REFIID aIid, IUnknown* aObject);
   AgileReference(AgileReference&& aOther);
 
@@ -54,31 +46,14 @@ public:
     return mAgileRef || mGitCookie;
   }
 
-  template <typename T>
-  void Assign(const RefPtr<T>& aOther)
-  {
-    Assign(__uuidof(T), aOther);
-  }
-
-  template <typename T>
-  AgileReference& operator=(const RefPtr<T>& aOther)
-  {
-    Assign(aOther);
-    return *this;
-  }
-
-  HRESULT Resolve(REFIID aIid, void** aOutInterface) const;
+  HRESULT Resolve(REFIID aIid, void** aOutInterface);
 
   AgileReference(const AgileReference& aOther) = delete;
   AgileReference& operator=(const AgileReference& aOther) = delete;
-
-  AgileReference& operator=(AgileReference&& aOther);
+  AgileReference& operator=(AgileReference&& aOther) = delete;
 
 private:
-  void Assign(REFIID aIid, IUnknown* aObject);
-  void AssignInternal(IUnknown* aObject);
-  void Clear();
-  static IGlobalInterfaceTable* ObtainGit();
+  IGlobalInterfaceTable* ObtainGit();
 
 private:
   IID                     mIid;
@@ -89,26 +64,4 @@ private:
 } // namespace mscom
 } // namespace mozilla
 
-template <typename T>
-RefPtr<T>::RefPtr(const mozilla::mscom::AgileReference& aAgileRef)
-{
-  void* newRawPtr;
-  if (FAILED(aAgileRef.Resolve(__uuidof(T), &newRawPtr))) {
-    newRawPtr = nullptr;
-  }
-  mRawPtr = static_cast<T*>(newRawPtr);
-}
-
-template <typename T>
-RefPtr<T>&
-RefPtr<T>::operator=(const mozilla::mscom::AgileReference& aAgileRef)
-{
-  void* newRawPtr;
-  if (FAILED(aAgileRef.Resolve(__uuidof(T), &newRawPtr))) {
-    newRawPtr = nullptr;
-  }
-  assign_assuming_AddRef(static_cast<T*>(newRawPtr));
-  return *this;
-}
-
 #endif // mozilla_mscom_AgileReference_h
diff --git a/ipc/mscom/Utils.cpp b/ipc/mscom/Utils.cpp
index 53da8540a528..6d4b32a4584d 100644
--- a/ipc/mscom/Utils.cpp
+++ b/ipc/mscom/Utils.cpp
@@ -32,15 +32,6 @@ extern "C" IMAGE_DOS_HEADER __ImageBase;
 namespace mozilla {
 namespace mscom {
 
-bool
-IsCOMInitializedOnCurrentThread()
-{
-  APTTYPE aptType;
-  APTTYPEQUALIFIER aptTypeQualifier;
-  HRESULT hr = CoGetApartmentType(&aptType, &aptTypeQualifier);
-  return hr != CO_E_NOTINITIALIZED;
-}
-
 bool
 IsCurrentThreadMTA()
 {
diff --git a/ipc/mscom/Utils.h b/ipc/mscom/Utils.h
index 5b6c0adfab18..b1ea77c77b8c 100644
--- a/ipc/mscom/Utils.h
+++ b/ipc/mscom/Utils.h
@@ -20,7 +20,6 @@ struct IUnknown;
 namespace mozilla {
 namespace mscom {
 
-bool IsCOMInitializedOnCurrentThread();
 bool IsCurrentThreadMTA();
 bool IsProxy(IUnknown* aUnknown);
 bool IsValidGUID(REFGUID aCheckGuid);
diff --git a/mfbt/RefPtr.h b/mfbt/RefPtr.h
index e0b05f1a3e62..4ba2854f1487 100644
--- a/mfbt/RefPtr.h
+++ b/mfbt/RefPtr.h
@@ -22,11 +22,6 @@ class nsISupports;
 namespace mozilla {
 template<class T> class OwningNonNull;
 template<class T> class StaticRefPtr;
-#if defined(XP_WIN)
-namespace mscom {
-class AgileReference;
-} // namespace mscom
-#endif // defined(XP_WIN)
 
 // Traditionally, RefPtr supports automatic refcounting of any pointer type
 // with AddRef() and Release() methods that follow the traditional semantics.
@@ -157,9 +152,6 @@ public:
 
   MOZ_IMPLICIT RefPtr(const nsQueryReferent& aHelper);
   MOZ_IMPLICIT RefPtr(const nsCOMPtr_helper& aHelper);
-#if defined(XP_WIN)
-  MOZ_IMPLICIT RefPtr(const mozilla::mscom::AgileReference& aAgileRef);
-#endif // defined(XP_WIN)
 
   // Defined in OwningNonNull.h
   template<class U>
@@ -223,9 +215,6 @@ public:
 
   RefPtr<T>& operator=(const nsQueryReferent& aQueryReferent);
   RefPtr<T>& operator=(const nsCOMPtr_helper& aHelper);
-#if defined(XP_WIN)
-  RefPtr<T>& operator=(const mozilla::mscom::AgileReference& aAgileRef);
-#endif // defined(XP_WIN)
 
   RefPtr<T>&
   operator=(RefPtr<T> && aRefPtr)
diff --git a/widget/windows/JumpListBuilder.cpp b/widget/windows/JumpListBuilder.cpp
index 8fce9560f74f..1f66c4a97d2c 100644
--- a/widget/windows/JumpListBuilder.cpp
+++ b/widget/windows/JumpListBuilder.cpp
@@ -20,10 +20,8 @@
 #include "nsThreadUtils.h"
 #include "mozilla/LazyIdleThread.h"
 #include "nsIObserverService.h"
-#include "mozilla/ScopeExit.h"
 #include "mozilla/Unused.h"
 #include "mozilla/dom/Promise.h"
-#include "mozilla/mscom/COMApartmentRegion.h"
 
 #include <shellapi.h>
 #include "WinUtils.h"
@@ -109,22 +107,10 @@ JumpListBuilder::JumpListBuilder() :
   mHasCommit(false),
   mMonitor("JumpListBuilderMonitor")
 {
-  MOZ_ASSERT(NS_IsMainThread());
+  ::CoInitialize(nullptr);
 
-  RefPtr<ICustomDestinationList> jumpListMgr;
-  HRESULT hr = CoCreateInstance(CLSID_DestinationList, nullptr,
-                                CLSCTX_INPROC_SERVER, IID_ICustomDestinationList,
-                                getter_AddRefs(jumpListMgr));
-  if (FAILED(hr)) {
-    return;
-  }
-
-  // Since we are accessing mJumpListMgr across different threads
-  // (ie, different apartments), mJumpListMgr must be an agile reference.
-  mJumpListMgr = jumpListMgr;
-  if (!mJumpListMgr) {
-    return;
-  }
+  CoCreateInstance(CLSID_DestinationList, nullptr, CLSCTX_INPROC_SERVER,
+                   IID_ICustomDestinationList, getter_AddRefs(mJumpListMgr));
 
   // Make a lazy thread for any IO
   mIOThread = new LazyIdleThread(DEFAULT_THREAD_TIMEOUT_MS,
@@ -143,6 +129,8 @@ JumpListBuilder::JumpListBuilder() :
 JumpListBuilder::~JumpListBuilder()
 {
   Preferences::RemoveObserver(this, kPrefTaskbarEnabled);
+  mJumpListMgr = nullptr;
+  ::CoUninitialize();
 }
 
 NS_IMETHODIMP JumpListBuilder::GetAvailable(int16_t *aAvailable)
@@ -176,19 +164,14 @@ NS_IMETHODIMP JumpListBuilder::GetMaxListItems(int16_t *aMaxItems)
     return NS_OK;
   }
 
-  RefPtr<ICustomDestinationList> jumpListMgr = mJumpListMgr;
-  if (!jumpListMgr) {
-    return NS_ERROR_UNEXPECTED;
-  }
-
   IObjectArray *objArray;
-  if (SUCCEEDED(jumpListMgr->BeginList(&mMaxItems, IID_PPV_ARGS(&objArray)))) {
+  if (SUCCEEDED(mJumpListMgr->BeginList(&mMaxItems, IID_PPV_ARGS(&objArray)))) {
     *aMaxItems = mMaxItems;
 
     if (objArray)
       objArray->Release();
 
-    jumpListMgr->AbortList();
+    mJumpListMgr->AbortList();
   }
 
   return NS_OK;
@@ -229,55 +212,36 @@ NS_IMETHODIMP JumpListBuilder::InitListBuild(JSContext* aCx,
 
 void JumpListBuilder::DoInitListBuild(RefPtr<Promise>&& aPromise)
 {
-  // Since we're invoking COM interfaces to talk to the shell on a background
-  // thread, we need to be running inside a single-threaded apartment.
-  mscom::STARegion sta;
-  MOZ_ASSERT(sta.IsValid());
-
   ReentrantMonitorAutoEnter lock(mMonitor);
   MOZ_ASSERT(mJumpListMgr);
 
-  if (sBuildingList) {
+  if(sBuildingList) {
     AbortListBuild();
   }
 
-  HRESULT hr = E_UNEXPECTED;
-  auto errorHandler = MakeScopeExit([&aPromise, &hr]() {
-    if (SUCCEEDED(hr)) {
-      return;
-    }
-
-    NS_DispatchToMainThread(NS_NewRunnableFunction("InitListBuildReject",
-                                                   [promise = std::move(aPromise)]() {
-      promise->MaybeReject(NS_ERROR_FAILURE);
-    }));
-  });
-
-  RefPtr<ICustomDestinationList> jumpListMgr = mJumpListMgr;
-  if (!jumpListMgr) {
-    return;
-  }
-
   nsTArray<nsString> urisToRemove;
   RefPtr<IObjectArray> objArray;
-  hr = jumpListMgr->BeginList(&mMaxItems,
-                              IID_PPV_ARGS(static_cast<IObjectArray**>
-                                           (getter_AddRefs(objArray))));
-  if (FAILED(hr)) {
-    return;
-  }
-
+  HRESULT hr = mJumpListMgr->BeginList(&mMaxItems,
+                                       IID_PPV_ARGS(static_cast<IObjectArray**>
+                                                    (getter_AddRefs(objArray))));
   // The returned objArray of removed items are for manually removed items.
   // This does not return items which are removed because they were previously
   // part of the jump list but are no longer part of the jump list.
-  sBuildingList = true;
-  RemoveIconCacheAndGetJumplistShortcutURIs(objArray, urisToRemove);
+  if (SUCCEEDED(hr)) {
+    sBuildingList = true;
+    RemoveIconCacheAndGetJumplistShortcutURIs(objArray, urisToRemove);
 
-  NS_DispatchToMainThread(NS_NewRunnableFunction("InitListBuildResolve",
-                                                 [urisToRemove = std::move(urisToRemove),
-                                                  promise = std::move(aPromise)]() {
-    promise->MaybeResolve(urisToRemove);
-  }));
+    NS_DispatchToMainThread(NS_NewRunnableFunction("InitListBuildResolve",
+                                                   [urisToRemove = std::move(urisToRemove),
+                                                    promise = std::move(aPromise)]() {
+      promise->MaybeResolve(urisToRemove);
+    }));
+  } else {
+    NS_DispatchToMainThread(NS_NewRunnableFunction("InitListBuildReject",
+                                                   [promise = std::move(aPromise)]() {
+      promise->MaybeReject(NS_ERROR_FAILURE);
+    }));
+  }
 }
 
 // Ensures that we have no old ICO files left in the jump list cache
@@ -330,11 +294,6 @@ NS_IMETHODIMP JumpListBuilder::AddListToBuild(int16_t aCatType, nsIArray *items,
   if (!mJumpListMgr)
     return NS_ERROR_NOT_AVAILABLE;
 
-  RefPtr<ICustomDestinationList> jumpListMgr = mJumpListMgr;
-  if (!jumpListMgr) {
-    return NS_ERROR_UNEXPECTED;
-  }
-
   switch(aCatType) {
     case nsIJumpListBuilder::JUMPLIST_CATEGORY_TASKS:
     {
@@ -379,7 +338,7 @@ NS_IMETHODIMP JumpListBuilder::AddListToBuild(int16_t aCatType, nsIArray *items,
         return NS_ERROR_UNEXPECTED;
 
       // Add the tasks
-      hr = jumpListMgr->AddUserTasks(pArray);
+      hr = mJumpListMgr->AddUserTasks(pArray);
       if (SUCCEEDED(hr))
         *_retval = true;
       return NS_OK;
@@ -387,14 +346,14 @@ NS_IMETHODIMP JumpListBuilder::AddListToBuild(int16_t aCatType, nsIArray *items,
     break;
     case nsIJumpListBuilder::JUMPLIST_CATEGORY_RECENT:
     {
-      if (SUCCEEDED(jumpListMgr->AppendKnownCategory(KDC_RECENT)))
+      if (SUCCEEDED(mJumpListMgr->AppendKnownCategory(KDC_RECENT)))
         *_retval = true;
       return NS_OK;
     }
     break;
     case nsIJumpListBuilder::JUMPLIST_CATEGORY_FREQUENT:
     {
-      if (SUCCEEDED(jumpListMgr->AppendKnownCategory(KDC_FREQUENT)))
+      if (SUCCEEDED(mJumpListMgr->AppendKnownCategory(KDC_FREQUENT)))
         *_retval = true;
       return NS_OK;
     }
@@ -461,7 +420,7 @@ NS_IMETHODIMP JumpListBuilder::AddListToBuild(int16_t aCatType, nsIArray *items,
         return NS_ERROR_UNEXPECTED;
 
       // Add the tasks
-      hr = jumpListMgr->AppendCategory(reinterpret_cast<const wchar_t*>(catName.BeginReading()), pArray);
+      hr = mJumpListMgr->AppendCategory(reinterpret_cast<const wchar_t*>(catName.BeginReading()), pArray);
       if (SUCCEEDED(hr))
         *_retval = true;
 
@@ -483,12 +442,7 @@ NS_IMETHODIMP JumpListBuilder::AbortListBuild()
   if (!mJumpListMgr)
     return NS_ERROR_NOT_AVAILABLE;
 
-  RefPtr<ICustomDestinationList> jumpListMgr = mJumpListMgr;
-  if (!jumpListMgr) {
-    return NS_ERROR_UNEXPECTED;
-  }
-
-  jumpListMgr->AbortList();
+  mJumpListMgr->AbortList();
   sBuildingList = false;
 
   return NS_OK;
@@ -517,33 +471,20 @@ NS_IMETHODIMP JumpListBuilder::CommitListBuild(nsIJumpListCommittedCallback* aCa
 
 void JumpListBuilder::DoCommitListBuild(RefPtr<detail::DoneCommitListBuildCallback> aCallback)
 {
-  // Since we're invoking COM interfaces to talk to the shell on a background
-  // thread, we need to be running inside a single-threaded apartment.
-  mscom::STARegion sta;
-  MOZ_ASSERT(sta.IsValid());
-
   ReentrantMonitorAutoEnter lock(mMonitor);
   MOZ_ASSERT(mJumpListMgr);
   MOZ_ASSERT(aCallback);
 
-  HRESULT hr = E_UNEXPECTED;
-  auto onExit = MakeScopeExit([&hr, &aCallback]() {
-    // XXX We might want some specific error data here.
-    aCallback->SetResult(SUCCEEDED(hr));
-    Unused << NS_DispatchToMainThread(aCallback);
-  });
-
-  RefPtr<ICustomDestinationList> jumpListMgr = mJumpListMgr;
-  if (!jumpListMgr) {
-    return;
-  }
-
-  hr = jumpListMgr->CommitList();
+  HRESULT hr = mJumpListMgr->CommitList();
   sBuildingList = false;
 
   if (SUCCEEDED(hr)) {
     mHasCommit = true;
   }
+
+  // XXX We might want some specific error data here.
+  aCallback->SetResult(SUCCEEDED(hr));
+  Unused << NS_DispatchToMainThread(aCallback);
 }
 
 NS_IMETHODIMP JumpListBuilder::DeleteActiveList(bool *_retval)
@@ -554,22 +495,15 @@ NS_IMETHODIMP JumpListBuilder::DeleteActiveList(bool *_retval)
   if (!mJumpListMgr)
     return NS_ERROR_NOT_AVAILABLE;
 
-  if (sBuildingList) {
+  if(sBuildingList)
     AbortListBuild();
-  }
 
   nsAutoString uid;
   if (!WinTaskbar::GetAppUserModelID(uid))
     return NS_OK;
 
-  RefPtr<ICustomDestinationList> jumpListMgr = mJumpListMgr;
-  if (!jumpListMgr) {
-    return NS_ERROR_UNEXPECTED;
-  }
-
-  if (SUCCEEDED(jumpListMgr->DeleteList(uid.get()))) {
+  if (SUCCEEDED(mJumpListMgr->DeleteList(uid.get())))
     *_retval = true;
-  }
 
   return NS_OK;
 }
@@ -620,7 +554,7 @@ void JumpListBuilder::RemoveIconCacheAndGetJumplistShortcutURIs(IObjectArray *aO
       int32_t numArgs;
 
       arglist = ::CommandLineToArgvW(buf, &numArgs);
-      if (arglist && numArgs > 0) {
+      if(arglist && numArgs > 0) {
         nsString spec(arglist[0]);
         aURISpecs.AppendElement(std::move(spec));
         ::LocalFree(arglist);
diff --git a/widget/windows/JumpListBuilder.h b/widget/windows/JumpListBuilder.h
index 064437e476f3..5140359a1cd8 100644
--- a/widget/windows/JumpListBuilder.h
+++ b/widget/windows/JumpListBuilder.h
@@ -23,7 +23,6 @@
 #include "nsIObserver.h"
 #include "nsTArray.h"
 #include "mozilla/Attributes.h"
-#include "mozilla/mscom/AgileReference.h"
 #include "mozilla/ReentrantMonitor.h"
 
 namespace mozilla {
@@ -49,7 +48,7 @@ protected:
   static Atomic<bool> sBuildingList;
 
 private:
-  mscom::AgileReference mJumpListMgr;
+  RefPtr<ICustomDestinationList> mJumpListMgr;
   uint32_t mMaxItems;
   bool mHasCommit;
   nsCOMPtr<nsIThread> mIOThread;